1. Field of the Invention
The present invention relates to relates to spinal fixation devices that are attached onto a patient's spine such as spinal rods and spinal rod screws (spinal rod assemblies) and, more particularly, to spinal cross connectors for attachment to adjacent spinal rod assemblies.
2. Background Information
There are many medical situations such as disease, injury, trauma or deformity, where it is necessary to align, hold, maintain and/or fix a desired relationship between adjacent vertebrae of the spine. In order to accomplish this goal, orthopedic spinal surgeons utilize spine fixation devices that are attachable to the posterior of various adjacent vertebrae of the affected area of the spine. These spine fixation devices provide the desired relationship between adjacent vertebrae. Spine fixation devices typically include a spinal fixation element, such as a relatively rigid fixation rod (e.g. a spine or spinal rod) that is connected to adjacent vertebrae through attachment of the rod to anchor devices (e.g. bone screw/rod head assemblies) implanted into the vertebrae. As such, spine fixation devices may be termed spine fixation assemblies.
Typically, spine fixation rods are placed on opposite sides of the spinous process in a substantially parallel relationship. The spine fixation rods may have pre-determined contours according to properties of the target implantation site and/or with regard to a desired spatial, vertebral relationship. The bone screw/rod head assemblies are typically implanted into the pedicle or pedicle area of the vertebra. Once installed, the spine fixation assemblies hold the vertebrae in a secure spatial relationship.
It may also be necessary in some circumstances, however, such as in cervical spine fixation applications, to provide a cross connector at one or more points between the two spine fixation assemblies in order to provide additional stability to the structure. Particularly, adjacent spinal fixation rod assemblies can be made more robust by using a cross connector to bridge the pair of spinal rod assemblies.
While current spinal cross connectors are effective, problems exist such as in mounting and maintaining the cross connector in a desired position and orientation with respect to the spinal rods. Other problems also exist with current cross connectors such as height limitations, sizing, locking and ease of installation issues.
Accordingly, there presently exists a need for an improved spinal cross connector that can be easily installed and securely attached to and between spinal rod fixation assemblies. There also presently exists a need for an improved spinal cross connector head assembly that can be easily installed onto a spinal rod bone screw head of a spinal rod bone screw head assembly.